The theory of Panspermia states that life is spread throughout the universe through stars, comets and other objects. When life forms on one planet, impacts can send the material into space, and then carry these seeds to other worlds. For decades, scientists have debated whether this could have happened between Earth and Mars (on both sides). However, recent controversy over the existence of biological life in Venus’ dense clouds has sparked discussions of interplanetary transfer between Venus, Earth and Mars.
In a recent study presented at 2026 Conference on Lunar and Planetary Science (LPSC), a team from The Johns Hopkins University Applied Physics Laboratory (JHUAPL) and Sandia National Laboratories explored this idea in detail. Using the “Venus Life Equation” (VLE) framework developed by Noam Izenberg et al. by 2021, the team’s models predict that life could exist in the clouds of Venus for at least a few days per hundred, thanks to material ejected from Earth.
Similar to the Drake Equation, the VLE decomposes the probability of life into a series of factors that (when multiplied) provide an estimate of the probability of life. Expressed numerically, VLE is divided as follows:
*### L = O x R x C*
Where L is the probability of Eternal Life (0 to 1, where 0 is unlikely and 1 is certain), O is Origin (the probability that life started and manifested itself on Venus), R is Robustness (the probability that the biosphere will exist and withstand changes), and C is Continuity (the probability that habitable conditions have continued until today). Using this framework, the first group considered how organisms, regardless of where they came from, must survive space travel.
*Some cloud layers on Venus support incredibly hospitable temperatures and pressures. Researchers have suggested that microbes may live in those clouds. Credit: ESA*
Along with the shock and trauma caused by the impact, there is also the heat generated during the process, as well as extreme heat, radiation and vacuum. However, computer modeling and studies of meteorites found on Earth have shown that living things can survive the impact and transfer of planets. By the time you get to Venus, any organic materials will also need to be dispersed into or above the clouds in order to survive.
With this in mind, the team’s calculations focused on how fireball meteorites (bolides) would fare in Venus’ atmosphere, taking into account removal, explosion, and fragmentation into pieces that could float in the clouds. They used the “pancake model” for this, a well-known semi-analytic method that describes the breakup of a bolide as it passes through the atmosphere. Once the bolide explodes in the atmosphere (“airburst”), aerodynamic drag spreads the fragments upward, creating a “pancake” of scattered material (which the team calls “cells”).
Using the pancake model and previous studies to find values for the first two phases, the team calculated the total number of bolides sent from Earth or Mars to the clouds of Venus. From this, they found that hundreds of billions of cells may have been transferred from Earth to the clouds of Venus, while hundreds of billions may remain viable. However, the best estimate of their kind that has been produced is that about 100 cells are scattered in the clouds of Venus per Earth year, while 20 billion cells would have been transferred from Earth 1 billion years ago.
Although the team admits that their model does not take into account all the details of space interactions, and that each parameter of the VLE has serious uncertainties (like the Drake Equation), it shows that panspermia between Earth and Venus is possible. Ergo, if future astronomy finds life in the clouds of Venus, chances are it originated on Earth.
Post Graduation: 2026 LPSC
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